Microphone transmitter



2 21, 1936. c PORTER 2,028,685

MICROPHONE TRANSMITTER Filed Dec. 24, 1934 INVENTOR Sleph-en Case Porier' B I KTTURNEY Patented Jan. 21, 1936 UNITED STATES z zaess PATENT OFFICE 8 Claims.

My invention relates to transmitters for magnifying sounds by the variation in electricalresistance caused by variation of pressure at a loose contact, and more particularly to transmitters for hearing aids designed to assist in the hearing of the deaf. I-Ieretofore, in transmitters of this class, the microphone has been mounted in a casing which was used as a sound box, the box or casing being provided with holes directly over the diaphragm, the sound waves enter the holes directly contacting with the diaphragm, causing it to vibrate. The mechanical vibrations are then converted into electrical impulses, as the diaphragm vibrations draw greater or less amount 15 of current from the battery. These impulses may be amplified in any well known means and conveyed through an electrical circuit to the ear piece where they set up vibrations of the ear piece diaphragm which reconverts the vibration 20 into sound waves.

are then conveyed through the air cushion in the ear to the ear drum. If the bone conduction method is used, instead of. the ear piece, a vibrator or oscillator is used, which vibrates the bones of the head without going through the ear.

Most persons afiiicted with deafness lose their sensitiveness in the higher range of vibrations, all sounds above middle C becoming blurred and confused. Therefore the deaf person while hearing quite distinctly the vowels, confuses the consonants and consequently misses most, if not all of the conversation, especially if he is not in a position to see the movements of the lips of the speaker.

All of the transmitters heretofore used have directed the sounds to be amplified directly on to the middle of the microphone diaphragm where the vibrations are the longest. This has 40 a tendency to amplify the low sounds, the sounds that the hearer already hears but does not help the confusion and blurring or distinctiveness of speech sought after by the deaf.

I have discovered that by forming my sound 45 box for my microphone apparatus so that the sound waves are directed away from the center of the diaphragm and conveyed through magnifying channels to the outer edge of the diaphragm, that the high notes are intensified and 50 the range of hearing aid is magnified many fold.

The main object of my invention is to produce a sound box for a microphone apparatus that will prevent the explosive sound heretofore common in devices now in use, one that will magnify the 55 sounds which the hard of hearing do need, at

These amplified sound waves the same time not to amplify the sounds which they now readily hear.

The foregoing and other features of my invention will now be described in connection with the accompanying drawing, forming part of this specification in which I have represented my microphone transmitter in its preferred form, after which I shall point out more particularly in the claims those features which I believe to be new and of my own invention. In the drawing:

Figure 1 is a front view of my transmitter.

Figure 2 is a section thereof along the line 2-2, Figure 1.

Figure 3 is a modification of the front face.

Figure 4 is a modified baflle which I may employ.

Figure 5 is a modified form shown in section similar to that shown in Figure 2.

Figure 6 is a back view of my transmitter showing the regulating switch which I may use to vary the resistance of my microphone apparatus. (Not shown.)

In the carrying out of my invention, I may conveniently mount any microphonic apparatus suitable for the purpose, upon a frame [0 which is adapted with means to support a vibrating diaphragm II. This frame is held in a case or sound box [2 and may be press fitted together as shown, or may be screw threaded in position as at l3. A face or cover M is provided with perforations l5 and is adapted to screw on the frame Ill.

Spaced apart from the face or cover I4, I provide a baffle I6 which may be supported in any manner. In Figure 2, I show the baflle l6 centrally supported to the cover as at IT, whereas in Figure 5, I show it supported from its periphery by three supports I1.

The curvature or shape of the baffle is substantially like the face or cover to which it is fastened and extends over the space containing the perforations, so that any sound waves entering the perforations are deflected along the baffle so they do not directly contact with the center of the diaphragm. This will prevent the explosive tones common to transmitters heretofore used.

To properly locate the baflle above the dia- I phragm, I provide a plurality of washers or other means 2i]. The distance can be readily varied by a greater or less number of washers used.

To obtain the best results, the radius of the baffle should be greater than the radius of the perforated area of the cover and I believe that it must be more than half the radius of the sound box cover.

My microphone apparatus is not shown as the details of such devices are well known to those skilled in the art, and such design will not in any way affect the operation of my invention.

In Figure 6 I show a back view of my box, which indicates a switch button used to operate the resistance of the electrical circuit in the microphone apparatus which I employ.

I wish it distinctly understood that my microphonic transmitter herein described and illustrated is in the form in which I desire to construct it and that changes or variations may be made as may be convenient or desirable without departing from the salient features of my invention and I therefore intend the following claims to cover such modifications as naturally fall within the lines of invention.

I claim:

1. The device of claim 5 with the addition of means for adjusting the distance between the bafile and the diaphragm.

2. The device of claim 5 with the baffle centrally mounted tothe face.

3. The device of claim 5 with the bafile mounted behind the face at the perimeter of the bafiie.

4. A transmitter of the class described, comprising the combination with a microphonlc apparatus having a diaphragm, of a sound box having a front face the center portion thereof semispherically shaped, a baffle plate substantially the same shape as the central portion of the face and held spaced apart from the face, and supported over the diaphragm.

5. A transmitter of the class described comprising the combination with a microphonic apparatus having a diaphragm, of a sound box having a front face, the center portion being raised outwardly from the face and provided with perforations, a baffle plate substantially the same shape as the raised portion and held spaced apart from the face and supported over the diaphragm.

6. The device of claim 5 with the raised portion of the front face perforated.

7. The device of claim 5 with the radius of the baffle, more than half the radius of the face.

8. The device of claim 5 with the baffle extending over the space of the face provided with perforations.

STEPHEN CASE PORTER. 

